An article from National Geographic - New Robot Reproduces on Its Own - takes on the issue of nanotechnology creating "grey goo". This is the substance, created by billions of nanobots, that could supposedly wipe out the planet in a matter of days according to the fears of some people who've looked at the surface of the topic.

What's fascinating about the article is it explores how these robots have actually self-reproduced and how this now reduces the unique capabilities of "life" or at the least, expands its definition. I realize this isn't related to search, but it's some worthwhile reading, nonetheless.